Selective metal deposition for electrochemical plating

ABSTRACT

A method and apparatus for plating metal onto a substrate including positioning an anode spacer including a anode surface and a substrate contact surface with the substrate contact surface immediate a deposition surface of a substrate. The apparatus generally includes a plating cell configured to contain a plating solution therein, an anode disposed in the plating solution, and an anode spacer positioned in the plating cell, the anode spacer having an anode surface, and a substrate contact surface positioned immediate a deposition surface of the substrate, the anode spacer configured to communicated the plating solution therethrough. The method generally includes positioning a substrate in a plating cell, positioning an anode spacer immediate a deposition surface of the substrate, and flowing a plating solution through the anode spacer to plate a metal onto the deposition surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to a method and apparatus for selectively depositing metals onto a substrate.

[0003] 2. Description of the Related Art

[0004] The production of sub-micron sized semiconductor features is a key technology for the next generation of very large scale integration (VLSI) and ultra large scale integration (ULSI) semiconductor devices. However, next generation ULSI and VLSI devices require a substantial decrease in interconnect dimensions, thereby imposing substantial manufacturing demands. Further, the features, such as vias and other interconnects, that lie at the heart of these technologies require precise processing. Reliable formation of these features is important to the success of VLSI and ULSI devices, and to the continued effort to increase circuit density and quality of individual substrates. Electroplating and electroless plating techniques have been found to efficiently and effectively fill features on semi-conductor devices.

[0005] Copper has a lower resistivity, e.g., 1.7 μΩ-cm compared to 3.1 μΩ-cm for aluminum, and can carry a higher current density than aluminum. Therefore, it is generally desirable to use copper to form interconnects in semiconductor devices, rather than aluminum. Conventional copper electroplating solutions typically consist of copper sulfate, sulfuric acid and additives to aid in depositing copper on the surface of a substrate and in filling sub-micron sized features, e.g., vias and interconnects. The additives may include any combination of, but not limited to, levelers, brighteners, inhibitors, suppressors, enhancers, accelerators, and surfactants. The additives are typically organic molecules that adsorb onto the surface of the substrate. Certain additives may decrease the ionization rate of metal atoms, thereby inhibiting the deposition process, whereas other additives may increase the deposition rate of metal.

[0006] One problem encountered in electroplating copper on a substrate is that the flow of electroplating solution over the substrate may not be uniform. Non-uniform flow of the electroplating solution provides uneven distribution of the copper ions to the substrate, which can lead to variations in the plating rate on the substrate. Variations in the plating rate may result in an uneven depth of copper deposition on the substrate. In addition, the substrate features often have an uneven topography, which may lead to voids in the feature upon plating.

[0007] There is a need, therefore, for an apparatus and a method for selectively depositing a metal onto a substrate to provide uniform metal deposition across the substrate.

SUMMARY OF THE INVENTION

[0008] Embodiments of the invention generally provide an apparatus for plating metal on a substrate having a plating cell configured to contain a plating solution therein, an anode disposed in the plating solution, and an anode spacer positioned in the plating cell. The anode spacer has an anode surface and a substrate contact surface positioned immediate a deposition surface of the substrate. The anode spacer is configured to communicate the plating solution to the surface of the substrate.

[0009] Embodiments of the invention further provide an apparatus for controlling metal deposition on a substrate. The apparatus includes an anode spacer, wherein the anode spacer has a periphery substantially equivalent to the periphery of the substrate. The anode spacer is generally configured to communicate a plating solution therethrough, and the anode spacer generally includes an anode surface and a substrate contact surface positioned immediate a deposition surface of the substrate.

[0010] Embodiments of the invention further provide a method for plating a metal on a substrate, wherein the method includes including positioning a substrate in a plating cell, positioning an anode spacer immediate a deposition surface of the substrate, and flowing a plating solution through the anode spacer to plate a metal onto the deposition surface.

[0011] Embodiments of the invention further provide an apparatus for plating metal on a substrate. The apparatus generally includes a plating cell configured to contain a plating solution therein, an anode disposed in the plating solution; and an anode spacer positioned in the plating cell. The anode spacer generally includes an anode surface, a substrate contact surface positioned a distance from a deposition surface of the substrate sufficient to uniformly plate a metal to a desired thickness, and a plurality of pores to communicate the plating solution to the deposition surface having an electrical resistance lower than the electrical resistance of the plating solution.

[0012] Embodiments of the invention further provide a method for plating a metal layer on a substrate. The method generally includes positioning a substrate having recessed locations and raised locations in a plating cell, positioning an anode spacer having a plurality of pores immediate a deposition surface of the substrate, and flowing a plating solution having a higher resistance than the plurality of pores through the plurality of pores, thereby plating the recessed locations until the substrate is in contact with the plurality of pores.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof, which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention, and are therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0014]FIG. 1 is a cross sectional view of a cell for electroplating a metal onto a substrate.

[0015]FIG. 2 is a cross sectional view of the anode spacer of an exemplary embodiment of the present invention.

[0016]FIG. 3 is a cross sectional view of the anode spacer of an alternative embodiment of the present invention.

[0017]FIG. 4 is a cross sectional view of the anode spacer of an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018]FIG. 1 illustrates a partial cross sectional schematic view of an exemplary electroplating cell 100 of the invention. The electroplating cell 100 generally includes a container body 142 having an opening on a top portion of the container body 142 to receive and support a lid 144. The container body 142 is preferably made of an electrically insulative material, such as a plastic, Teflon, or ceramic. The lid 144 serves as a top cover having a substrate supporting surface 146 disposed on the lower portion thereof. A substrate 148 is shown in parallel abutment to the substrate supporting surface 146, and may be secured in this orientation via conventional substrate chucking methods. The container body 142 is preferably cylindrically shaped in order to accommodate the generally circular substrate 148 at one end thereof. However, other substrate shapes can be used as well.

[0019] An electroplating solution inlet 150 is disposed at the bottom portion of the container body 142. An electroplating solution may be pumped into the container body 142 by a suitable pump 151 connected to the inlet 150. The solution may flow upwardly inside the container body 142 toward the substrate 148 to contact the exposed deposition surface 154. A consumable anode 156 may be disposed in the container body 142 and configured to dissolve in the electroplating solution in order to provide metal particles to be deposited onto the substrate 148 to the plating solution. The anode 156 generally does not extend across the entire width of the container body 142, thus allowing the electroplating solution to flow between the outer surface of the anode 156 and the inner surface of the container body 176 to the deposition surface 154. Alternatively, an anode 156 consisting of an electrode and consumable metal particles may be encased in a fluid permeable membrane, such as a porous ceramic plate, to provide metal particles to be deposited onto the substrate to the plating solution. A porous non-consumable anode may also be disposed in the container body 142 so that the electroplating solution may pass therethrough. However, when a non-consumable anode is included, the electroplating solution should include a metal particle supply to continually replenish the metal particles to be deposited on the substrate 148.

[0020] The container body 142 generally includes an egress gap 158 bounded at an upper limit by a shoulder 164 of a cathode contact ring 152. The gap 158 generally leads to an annular weir 143 that is substantially coplanar with (or slightly above) the substrate seating surface 168, and thus, the deposition surface 154. The weir 143 is positioned to ensure that the deposition surface 154 is in contact with the electroplating solution when the electroplating solution is flowing out of the egress gap 158 and over the weir 143. During processing, the substrate 148 is secured to the substrate supporting surface 146 of the lid 144 by a plurality of vacuum passages 160 formed in the surface 146, wherein passages 160 are generally connected at one end to a vacuum pump (not shown). The cathode contact ring 152, which is shown disposed between the lid 144 and the container body 142, is connected to a power supply 149 to provide power to the substrate 148. The contact ring 152 generally has a perimeter flange 162 partially disposed through the lid 144, a sloping shoulder 164 conforming to the weir 143, and an inner substrate seating surface 168, which defines the diameter of the deposition surface 154. The shoulder 164 is provided so that the inner substrate seating surface 168 is located below the flange 162. This geometry allows the deposition surface 154 to come into contact with the electroplating solution before the solution flows into the egress gap 158 as discussed above. However, as noted above, the contact ring design may be varied from that shown in FIG. 1 without departing from the scope of the present invention. Thus, the angle of the shoulder portion 164 may be altered or the shoulder portion 164 may be eliminated altogether so that the contact ring is substantially planar. Where a planar design is used, seals may be disposed between the contact ring 152, the container body 142 and/or the lid 144 to form a fluid tight seal therebetween.

[0021] The substrate seating surface 168 preferably extends a minimal radial distance inward below a perimeter edge of the substrate 148, but a distance sufficient to establish electrical contact with a metal seed layer on the substrate deposition surface 154. The exact inward radial extension of the substrate seating surface 168 may be varied according to application. However, in general this distance is minimized so that a maximum deposition surface 154 is exposed to the electroplating solution. In an exemplary embodiment, the radial width of the seating surface 168 is 2 mm from the edge.

[0022] Embodiments of the invention further include an anode spacer 170 disposed between the anode 156 and the deposition surface 154. The anode spacer 170 includes and anode surface 172 and a substrate contact surface 174. The anode surface 172 is positioned facing the anode 156. The substrate contact surface 174 is positioned immediate the deposition surface of the substrate 154. As used herein, substrate contact surface 174 generally refers to the surface of the anode spacer 170 nearest the deposition surface 154. The substrate contact surface 174 is defined further in reference to the specific embodiments described below. As used herein, “immediate” refers to the substrate contact surface 174 being in physical contact and generally parallel to the deposition surface 154 when the substrate has been plated to a desired thickness, i.e., the substrate contact surface 174 may be in physical contact with the deposition surface 154 in some locations and may not be in physical contact with the deposition surface 154 in other locations, at any given time during plating, but substantially all of the substrate contact surface 174 will be in physical contact with the deposition surface 154 when the plating is complete.

[0023] The anode spacer 170 is generally constructed to be substantially rigid, wherein, the term “rigid” indicates sufficient structural rigidity of the anode spacer 170 to limit deformation or bending of the anode spacer 170 under the normal operational conditions in the process cell 100. Such deformation would bend the anode spacer 170 so that the center is nearer the nearest location on the substrate 148 than the periphery is to its closest location on the substrate 148. The anode spacer 170 generally has a periphery substantially equivalent to the periphery of the substrate 148. The anode spacer 170 may be formed from any suitable, nonconductive, substantially rigid material, such as PEEK, i.e., polyethelether ketone, commercially available from Victrex, of Greenville, S.C., for example, or similar plastic materials.

[0024] The anode spacer 170 may be any vertical height and width sufficient to position the substrate contact surface 174 immediate with the deposition surface of the substrate 154. The anode spacer's 170 vertical height may be between about 1 inch and about 12 inches. The anode spacer 170 may be disposed at any location in the container body 142 so that the substrate contact surface 174 is positioned immediate with deposition surface 154. For example, the substrate contact surface 174 of the anode spacer 170 may be positioned to physically contact the thickest portions of the deposition surface prior to plating 154, or the anode spacer 170 may be positioned so that the substrate contact surface 174 is a predetermined distance away from the thickest portion of the deposition surface 154, where the predetermined distance is equal to a distance that will provide a desired thickness copper to be plated on the substrate 148. In another embodiment, the anode spacer 170 may be positioned between the substrate seating surfaces 168. It is also envisioned that the anode spacer 170 may be positioned above the inner substrate seating surface 168, below and in contact with the substrate 148. The anode spacer 170 may also be located anywhere in the container body 142 between the anode 156 and the substrate 148, such that the substrate contact surface 174 is positioned immediate the deposition surface 154. In an alternative embodiment, the anode spacer 170 may be secured to the cylindrical wall of the container body 142 so that the substrate contact surface 174 is immediate the deposition surface 146. The anode spacer 170 may be applied to various process cells, having various anode configurations.

[0025] Embodiments of the invention further contemplate rotating the anode spacer 170 in relation to the substrate 148, thereby providing more uniform metal deposition on the deposition surface 154. Rotating the anode spacer 170 ensures that all locations on the deposition surface 154 have an even layer of metal deposition. Alternatively, the anode spacer 170 may be moved horizontally in relation to the substrate 148 to provide uniform metal deposition on the deposition surface 154. Further still, the anode spacer 170 may be agitated to provide uniform metal deposition of the deposition surface 154.

[0026]FIG. 2 illustrates a cross sectional view of a substrate 148 and an anode spacer 170. The anode spacer 170 includes a plurality of pores 200, through which the plating solution flows. Substantially all of the plating solution flows through the pores to contact the substrate deposition surface 154. The pores are sized to permit ions generated by the anode 156 to pass therethrough. However, larger portions of the anode 156, such as shavings, by-products, and other debris remaining in the solution (otherwise known collectively as anode sludge), do not flow through the anode spacer 170, thereby keeping them from contacting the deposition surface 154. The anode spacer 170 is designed with pores 200 having a diameter of between about 0.25 inches and about 1 inch. The anode spacer 170 may be formed of a metal, alloy, ceramic, plastic, or other suitable material. Although relatively few pores 200 are depicted in FIG. 2, in actuality, there may actually be a much larger number of pores 200. Preferably, the pores 200 are arranged in a geometric array, and are horizontally spaced from each neighboring pore 200 by about {fraction (1/10)} to about ½ of the pore's diameter. The pores 200 are generally of equal length and diameter. The substrate contact surface 174 of the anode spacer 170 is located adjacent the substrate deposition surface 154, although the substrate contact surface 174 may be positioned a distance from the deposition surface 154 equal to the desired thickness of metal to be plated. The substrate contact surface 174 extends substantially across the anode spacer 170.

[0027] The pores 200 may be lined with a conductive material to deliver electrical current from the anode 156 to the deposition surface 154 via the conductive pore surface or via the electroplating solution flowing through the pore 200. The conductive pore lining may include any suitable conductive material for communicating plating solution therethrough, without attracting metal ions from the plating solution. The conductive material may be a metal, such as gold, platinum, or graphite.

[0028] In operation, the contact ring 152 is negatively charged to act as a cathode. As the electroplating solution is flowed across the substrate surface 154, the ions in the electroplating solution are attracted to the surface 154 by the negative charge. The ions then react with the surface 154 to form the desired film. In addition to the anode 156 and the cathode contact ring 152, an auxiliary electrode 167 may be used to control the shape of the electrical field over the deposition surface 154. An auxiliary electrode 167 is shown disposed through the container body 142 adjacent an exhaust channel 169. By positioning the auxiliary electrode 167 adjacent to the exhaust channel 169, the electrode 167 able to maintain contact with the electroplating solution during processing and affect the electrical field.

[0029] Generally, ionic current flows to the deposition surface 154 via the conductive pore surface. At recessed substrate locations 204, the pore lining is not in contact with the deposition surface 154, therefore ionic current and electroplating solution flow to the deposition surface 154. As a result, plating proceeds. When the conductive pore 200 is in contact with the deposition surface 154, i.e., at raised substrate locations 202, ionic current does not flow to the deposition surface 154, and therefore, no metal is plated on the substrate 148 at that location 202. Therefore, plating will continue at the recessed location 204 until the conductive lining of the pore 200 is in contact with the substrate deposition surface 154, thereby filling the recessed locations 202 and forming a uniform metal layer on the substrate 148.

[0030] In one embodiment, the resistance of the pores 200 is lower than the resistance of the electroplating solution in order to maximize the ionic current traveling to the deposition surface 154 via the conductive pore lining. Maximizing the electrical current traveling via the pore lining ensures that the recessed areas of the deposition surface 204 will plate until the pore 200 is in contact with the deposition surface 154. At the point that the pore 200 contacts the deposition surface 154, plating ceases because insufficient ionic current will travel to the deposition surface 154 to plate the metal. In an exemplary embodiment of the invention, the resistance of the conductive pores is about 10 times less than the resistance of the electroplating solution, thereby providing a higher current traveling to the lowest substrate surfaces via the pore lining.

[0031] Alternative embodiments of the invention may include a plurality of anode spacers 170 located immediate the deposition surface 154. A plurality of anode spacers 170 may be included to provide local uniformity to individual portions of the deposition surface 154, rather than having the highest portion of the deposition surface 154 determine the thickness of the entire substrate 148. The spacers 170 may be positioned to cooperatively cover the deposition surface, either when stationary or upon rotation.

[0032]FIG. 3 illustrates an alternative embodiment of the present invention. In this embodiment, the conductive inner surface of the pores 300 extends beyond the body of the anode spacer 170. The plating solution flows from the anode 156 through the extended pores 300 to the deposition surface 154. The substrate contact surface 174 is the position on the pore 300 closest the deposition surface, i.e., the part of the anode spacer 170 that will contact the deposition surface 154. The pore extensions are generally of equal length and consist of the same conductive material as the body of the pore 300. Alternative embodiments of the invention contemplate pores 300 of varying length, e.g., the pores 300 may be spring loaded 302, to provide varying levels of local uniformity to the substrate 148. Metal deposition generally will not occur on the pore extensions, because the conductive material is such that it does not attract metal ions. An example of a suitable material is graphite. The pore extensions may continue from the pore body or may be separate from the pore body.

[0033] Generally, current flows to the deposition surface 154 via the conductive pore extensions. At recessed substrate locations 204, ionic current flows to the deposition surface 154, and therefore, plating proceeds. When the conductive pore lining 300 is in contact with the deposition surface 154, i.e., at raised substrate locations 202, ionic current no longer flows to the deposition surface 154, and therefore, no metal is plated on the substrate 148 at that location 202. As a result, plating will continue at the recessed locations 204 until the conductive lining of the pore 300 is in contact with the substrate deposition surface 154, thereby filling the recessed locations 202 and forming a uniform metal layer on the substrate 148.

[0034]FIG. 4 illustrates another embodiment of the present invention. The anode spacer 170 does not include pores, and therefore, no electroplating solution flows through the anode spacer 170. In this embodiment, the anode spacer 170 comprises a plurality of cylindrical spacers consisting of a conductive material that are configured to extend from the anode 156 to the substrate deposition surface 154. The conductive material may include any suitable conductive material conducting electrical current, without attracting metal ions from the plating solution. The conductive material may be a metal, such as gold, platinum, or graphite. No metal deposition will occur on the anode spacers 170 because the conductive material is such that it does not attract metal ions.

[0035] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

What is claimed is:
 1. An apparatus for plating metal on a substrate, comprising: a plating cell configured to contain a plating solution therein; an anode disposed in the plating solution; and an anode spacer positioned in the plating cell, the anode spacer comprising: an anode surface; and a substrate contact surface positioned immediate a deposition surface of the substrate, the anode spacer configured to communicate the plating solution therethrough.
 2. The apparatus of claim 1, wherein the anode spacer is substantially rigid.
 3. The apparatus of claim 1, wherein the anode spacer has a periphery substantially equivalent to a periphery of the substrate.
 4. The apparatus of claim 1, wherein the substrate contact surface is positioned a distance from the substrate deposition surface equal to the thickness of the metal to be plated on the deposition surface.
 5. The apparatus of claim 1, wherein an electrical current passes through a plurality of conductive pores formed into the anode spacer.
 6. The apparatus of claim 1, wherein an electrical current passes through a plurality of conductive pores formed in the anode spacer and the plurality of conductive pore have an electrical resistance lower than an electrical resistance of the plating solution.
 7. The apparatus of claim 1, wherein a plurality of pores disposed in the anode spacer interconnect the anode surface and the substrate contact surface.
 8. The apparatus of claim 7, wherein each of the plurality of pores are of equal longitudinal length.
 9. The apparatus of claim 7, wherein each of the plurality of pores are of equal diameter.
 10. The apparatus of claim 7, wherein the plurality of pores are lined with a conductive material.
 11. The apparatus of claim 7, wherein the plurality of pores are lined with at least one of gold, platinum, and graphite.
 12. The apparatus of claim 7, wherein the plurality of pores are lined with a conductive material extending past the substrate contact surface.
 13. The apparatus of claim 12, wherein the plurality of pores have an adjustable length.
 14. The apparatus of claim 12, wherein each of the plurality of pores are lined with graphite extending past the substrate contact surface an equal longitudinal distance.
 15. The apparatus of claim 1, wherein the anode spacer comprises a plurality of anode spacers.
 16. The apparatus of claim 1, wherein the anode spacer further comprises a plurality of spacers extending from the anode toward the deposition surface.
 17. The apparatus of claim 16, wherein the plurality of spacers are composed of a conductive material.
 18. The apparatus of claim 16, wherein the plurality of spacers are composed of a conductive material selected from the group essentially comprising gold, platinum, and graphite.
 19. A method for plating a metal layer on a substrate, comprising: positioning a substrate in a plating cell; positioning an anode spacer immediate a deposition surface of the substrate; and flowing a plating solution through the anode spacer to plate a metal onto the deposition surface.
 20. The method of claim 19, further comprising rotating the anode spacer in relation to the deposition surface.
 21. The method of claim 19, wherein flowing a plating solution through the anode spacer comprises flowing the plating solution through a plurality of pores extending through the anode spacer.
 22. The method of claim 19, wherein flowing a plating solution through the anode spacer comprises flowing the plating solution through a plurality of pores extending through the anode spacer lined with a conductive material.
 23. The method of claim 19, wherein flowing a plating solution through the anode spacer comprises flowing the plating solution through a plurality of pores extending through the anode spacer lined with a conductive material selected from the group essentially comprising gold, platinum, and graphite.
 24. The method of claim 19, further comprising generating an electrical bias between an anode and the substrate.
 25. The method of claim 19, further comprising generating an electrical current to pass from an anode to the substrate through a plurality of conductive pores in the anode spacer.
 26. The method of claim 19, wherein the metal is copper.
 27. The method of claim 19, wherein positioning the anode spacer comprises positioning a plurality of anode spacers.
 28. The method of claim 19, wherein positioning the anode spacer comprises positioning a plurality of anode spacers in contact with the anode extending toward the deposition surface.
 29. The method of claim 28, wherein the plurality of spacers are composed of a conductive material.
 30. The method of claim 28, wherein the plurality of spacers are composed of gold, platinum, or graphite, or a combination thereof.
 31. An apparatus for controlling metal deposition on a substrate, comprising an anode spacer, wherein the anode spacer has a periphery substantially equivalent to the periphery of the substrate, the anode spacer is configured to communicate a plating solution therethrough, and the anode spacer includes an anode surface and a substrate contact surface positioned immediate a deposition surface of the substrate.
 32. The apparatus of claim 31, wherein the anode spacer is substantially rigid.
 33. The apparatus of claim 31, wherein a plurality of pores interconnect the anode surface and the substrate contact surface.
 34. The apparatus of claim 33, wherein each of the plurality of pores are of equal longitudinal length.
 35. The apparatus of claim 33, wherein each of the plurality of pores are of equal diameter.
 36. The apparatus of claim 33, wherein the plurality of pores are lined with a conductive material.
 37. The apparatus of claim 33, wherein the plurality of pores are lined with gold, platinum, or graphite, or a combination thereof.
 38. The apparatus of claim 33, wherein the plurality of pores are lined with a conductive material extending beyond the substrate contact surface.
 39. The apparatus of claim 38, wherein the plurality of pores have an adjustable length.
 40. The apparatus of claim 33, wherein each of the plurality of pores are lined with graphite extending past the substrate contact surface an equal longitudinal distance.
 41. The apparatus of claim 31, wherein the anode spacer comprises a plurality of anode spacers.
 42. The apparatus of claim 31, wherein the anode spacer further comprises a plurality of cylindrical spacers of equal longitudinal length and diameter.
 43. The apparatus of claim 42, wherein the plurality of spacers are composed of a conductive material.
 44. The apparatus of claim 42, wherein the plurality of spacers are composed of a conductive material selected from the group essentially comprising gold, platinum, and graphite.
 45. An apparatus for plating metal on a substrate, comprising: a plating cell configured to contain a plating solution therein; an anode disposed in the plating solution; and an anode spacer positioned in the plating cell, the anode spacer comprising: an anode surface; a substrate contact surface positioned a distance from a deposition surface of the substrate sufficient to uniformly plate a metal to a desired thickness; and a plurality of pores to communicate the plating solution to the deposition surface having an electrical resistance higher than the electrical resistance of the plating solution.
 46. The apparatus of claim 45, wherein the anode spacer is substantially rigid.
 47. The apparatus of claim 45, wherein the anode spacer has a periphery substantially equivalent to a periphery of the substrate.
 48. The apparatus of claim 45, wherein the plurality of pores are of equal longitudinal length.
 49. The apparatus of claim 45, wherein each of the plurality of pores are of equal diameter.
 50. The apparatus of claim 45, wherein the plurality of pores are lined with a conductive material.
 51. The apparatus of claim 45, wherein the plurality of pores are lined with at least one of gold, platinum, and graphite.
 52. The apparatus of claim 45, wherein the plurality of pores are lined with a conductive material extending past the substrate contact surface.
 53. The apparatus of claim 52, wherein the plurality of pores have an adjustable length.
 54. The apparatus of claim 52, wherein each of the plurality of pores are lined with graphite extending past the substrate contact surface an equal longitudinal distance.
 55. The apparatus of claim 45, wherein the anode spacer comprises a plurality of anode spacers.
 56. A method for plating a metal layer on a substrate, comprising: positioning a substrate having recessed locations and raised locations in a plating cell; positioning an anode spacer having a plurality of pores immediate a deposition surface of the substrate; and flowing a plating solution having a higher resistance than the plurality of pores through the plurality of pores thereby plating the recessed locations until the substrate is in contact with the plurality of pores.
 57. The method of claim 56, further comprising rotating the anode spacer in relation to the deposition surface.
 58. The method of claim 56, wherein the plurality of pores extend through the anode spacer.
 59. The method of claim 56, wherein flowing a plating solution through the plurality of pores comprises flowing the plating solution through a plurality of pores lined with a conductive material extending through the anode spacer.
 60. The method of claim 56, wherein flowing a plating solution through the plurality of pores comprises flowing the plating solution through a plurality of pores extending through the anode spacer lined with a conductive material selected from the group essentially comprising gold, platinum, and graphite.
 61. The method of claim 56, wherein positioning the anode spacer comprises positioning a plurality of anode spacers in contact with the anode extending toward the deposition surface.
 62. The method of claim 61, wherein the plurality of spacers are composed of a conductive material. 